Start by heating the olive oil in a large, heavy-based casserole dish over medium heat. Add the bacon lardons and cook until golden and crispy, then remove and set aside.

Season the onglet pieces with salt and black pepper, then sear them in the same pan until browned on all sides. Remove and set aside with the bacon.

Lower the heat and melt the butter in the pan. Add the shallots and cook until they begin to caramelise. Stir in the garlic and cook for another minute before adding the mushrooms.

Sprinkle the flour over the shallots and mushrooms, stirring well to coat everything evenly. Add the tomato purée and cook for a further minute to deepen the flavour.

Return the beef and bacon to the pot, then pour in the red wine and beef stock. Stir well, making sure to scrape up any caramelised bits from the bottom of the pan.

Tie the bay leaves, thyme, and rosemary together with kitchen twine and drop them into the pot. Bring to a gentle simmer, cover, and cook on low heat for 2 hours, stirring occasionally, until the beef is meltingly tender.

Once cooked, remove the herb bundle and check the seasoning. If the sauce needs thickening, simmer uncovered for a few more minutes until reduced to your liking.